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High-Efficiency Ion-Exchange Doping of Conducting Polymers.

Accepted version
Peer-reviewed

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Authors

Jacobs, Ian E 
Lin, Yue 
Huang, Yuxuan 
Ren, Xinglong 
Simatos, Dimitrios 

Abstract

Molecular doping-the use of redox-active small molecules as dopants for organic semiconductors-has seen a surge in research interest driven by emerging applications in sensing, bioelectronics, and thermoelectrics. However, molecular doping carries with it several intrinsic problems stemming directly from the redox-active character of these materials. A recent breakthrough was a doping technique based on ion-exchange, which separates the redox and charge compensation steps of the doping process. Here, the equilibrium and kinetics of ion exchange doping in a model system, poly(2,5-bis(3-alkylthiophen-2-yl)thieno(3,2-b)thiophene) (PBTTT) doped with FeCl3 and an ionic liquid, is studied, reaching conductivities in excess of 1000 S cm-1 and ion exchange efficiencies above 99%. Several factors that enable such high performance, including the choice of acetonitrile as the doping solvent, which largely eliminates electrolyte association effects and dramatically increases the doping strength of FeCl3 , are demonstrated. In this high ion exchange efficiency regime, a simple connection between electrochemical doping and ion exchange is illustrated, and it is shown that the performance and stability of highly doped PBTTT is ultimately limited by intrinsically poor stability at high redox potential.

Description

Keywords

conjugated polymers, doping, electrical conductivity, electrochemistry, ion exchange

Journal Title

Adv Mater

Conference Name

Journal ISSN

0935-9648
1521-4095

Volume Title

Publisher

Wiley
Sponsorship
European Research Council (610115)
Engineering and Physical Sciences Research Council (EP/L015889/1)
Engineering and Physical Sciences Research Council (EP/R031894/1)
Engineering and Physical Sciences Research Council (EP/P024947/1)
Engineering and Physical Sciences Research Council (EP/S019367/1)
Engineering and Physical Sciences Research Council (EP/R00661X/1)
Engineering and Physical Sciences Research Council (EP/P007767/1)
Royal Society Newton International Fellowship (Grant NF170736) European Research Council Synergy grant SC2 (no. 610115) Engineering and Physical Sciences Research Council (EP/R031894/1)
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